Sign up to receive free email alerts when patent applications with chosen keywords are publishedSIGN UP

Abstract:

An electrically adjustable optical diffusion panel for use in film or
video production having a frame, diffusion material affixed to the frame,
where the transparency of the material is continuously and variably
changeable between a substantially transparent state and a substantially
opaque state in response to an electric potential applied to electrodes
of the material and a controller and battery. The electrically adjustable
diffusion panel eliminates the need for manually changing diffusion
papers or other filters and provides a continuous range of selectable
levels of transparency/diffusion.

Claims:

1. An electrically adjustable optical diffusion panel for luminaires used
in a film or video production, the panel comprising: (a) a frame defining
an area through which incident light from a film or video production
light source passes to become transmitted light thereafter; (b) diffusion
material affixed to said frame and covering at least some of said area,
said diffusion material having its transparency continuously and variably
changeable between a substantially transparent state and a substantially
opaque state in response to an electric potential applied to electrodes
of said diffusion material; and (c) a controller having circuitry adapted
to provide said electric potential and a battery electrically
interconnected with the circuitry.

2. The diffusion panel of claim 1 wherein said substantially transparent
state provides a substantially clear panel through which said light
source is visible to a subject of said film or video production and
shadows cast by said light source have sharp definition.

3. The diffusion panel of claim 1 wherein said substantially opaque state
provides a substantially opaque panel through which said light source is
not visible to a subject of said film or video production and shadows
cast by said light source have indistinct definition.

4. The diffusion panel of claim 1 wherein said diffusion material is
detachable from said frame and flexible enough to allow said material to
be rolled into a tube.

5. The diffusion panel of claim 1 wherein said diffusion material
provides transparency equivalent of 1/4 stop, 3/4 stop, and full stop
diffusion paper in response to a user of said panel selecting said
electric potential with said controller so as to vary said transparency
to be equivalent to said 1/4 stop, 3/4 stop, and full stop diffusion
paper.

6. The diffusion panel of claim 5 wherein an exterior visual appearance
of said diffusion material when not in a fully transparent mode is milky
white.

7. The diffusion panel of claim 1 wherein said controller is a handheld
sized device with a voltage control rotary knob.

8. The diffusion panel of claim 1 wherein said controller is a handheld
sized device and said battery is a standard 9 volt battery.

9. The diffusion panel of claim 1 wherein said diffusion material
comprises a polymer dispersed liquid crystal layer having a front surface
area and a rear surface area, transparent conductive layers on both of
said front and rear surface areas, and electrical connections between
said conductive layers and said controller circuitry.

10. The diffusion panel of claim 9 wherein said liquid crystal layer
becomes more transparent as voltage is increased across said electrical
connections between said conductive layers.

11. The diffusion panel of claim 9 wherein said liquid crystal layer
becomes substantially opaque when voltage is zero across said electrical
connections between said conductive layers.

12. The diffusion panel of claim 1 further comprising circuitry adapted
to wirelessly receive signals and change said electric potential applied
to said electrodes in response thereto.

13. A method of diffusing light incident to a subject of a film or video
production comprising the steps of: (a) placing a diffusion panel between
a light source and said subject, said diffusion panel comprising (i) a
frame defining an area through which incident light from said light
source passes to become transmitted light thereafter, (i) diffusion
material affixed to said frame and covering at least some of said area,
said diffusion material having its transparency changeable between a
substantially transparent state and a substantially opaque state in
response to an electric potential applied to electrodes of said diffusion
material, and (iii) a controller having circuitry adapted to provide said
electric potential and a battery electrically interconnected with the
circuitry; (b) energizing said light source so as to direct incident
light therefrom through said diffusion panel; and (c) electrically
adjusting the transparency of said diffusion panel by changing said
electric potential using said controller.

14. The method of claim 13 wherein using said controller comprises
rotating a knob on a handheld sized unit comprising said controller.

15. The method of claim 13 wherein said substantially transparent state
provides a substantially clear panel through which said light source is
visible to said subject of said film or video production and shadows cast
by said light source have sharp definition.

16. The method of claim 13 wherein said substantially opaque state
provides a substantially opaque panel through which said light source is
not visible to a subject of said film or video production and shadows
cast by said light source have indistinct definition.

17. The method of claim 13 further comprising (d) detaching said
diffusion material from said frame and rolling said material into a tube.

18. The method of claim 17 further comprising (e) unrolling said
diffusion material and re-attaching said diffusion material to said
frame, wherein said diffusion material continues to operate with its
transparency changeable between said substantially transparent state and
said substantially opaque state in response to said electric potential
applied to electrodes of said diffusion material, as before said step of
detaching and rolling said material into said tube.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] None

BACKGROUND OF THE INVENTION

[0002] This disclosure relates to light diffusion techniques used in the
film and video production industry and, more particularly, to diffusion
of light sources used in film or video production using materials having
electrically adjustable light diffusion characteristics.

[0003] Lighting techniques used in the production of film and video have
long been carefully and diligently studied by the artists, technologists,
and other professionals practicing in the film and video industry.
Careful attention is paid to the creation of lighting conditions so as to
achieve particular desired effects. Volumes have been written about the
characteristics of light most preferred in a given situation, how various
environmental or set conditions impact lighting quality, the
considerations that should be given depending upon the subject of the
film or video, and so on. Volumes more may be written of the particular
equipment preferences that those responsible for lighting on a film or
video crew use to accommodate various circumstances. In a conventional
motion picture production, the gaffer or lead person on the electrical
crew, for example, may work closely with the crew best boy, grips, and
other electricians to design and build the lighting setup for a
particular production, using experience and industry trade practices to
determine the appropriate gels and diffusion materials to put on lights
or windows to achieve the desired effects, or to determine whether or not
to use various materials and equipment to re-create particular natural
effects within a better controlled stage or to adapt such materials and
equipment to allow for on-location filming. Much of the expertise of such
professionals is likely maintained as closely held tricks of the trade
and other proprietary information.

[0004] What may be generally true is that innovative approaches to film
and video production have been widely sought after and favorably received
by the film and video industry in the U.S., particularly where such
innovations provide improvements in costs so as to lower overall
production costs; improvements in the features and functionality
available to the users of newly developed equipment; improvements in
quality of equipment or reliability of the equipment or the processes of
using various equipment; and improvements in the speed with which film
and video production may be successfully completed.

[0005] Some of the more labor intensive aspects of film and video
production involve engineering lighting effects that deliver desired
results, accommodate physical space requirements of the set, and provide
means for adapting to changes in set conditions such as weather, natural
light position, camera angles, and subject position throughout a scene,
and other factors requiring, ideally, instant changes in lighting
provided for the shoot. The lighting equipment used should be
reconfigurable to accommodate a range of different physical space
requirements and adaptable to changing set conditions with a minimum of
labor.

[0006] What is needed, therefore, are light diffusion techniques and
equipment for the diffusion of light sources used in film or video
production that address various shortcomings of existing techniques and
equipment. The foregoing and other objectives, features, and advantages
of the invention will be more readily understood upon consideration of
the following detailed description of the invention taken in conjunction
with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL DRAWINGS

[0007] For a more complete understanding of the present invention, the
drawings herein illustrate examples of the invention. The drawings,
however, do not limit the scope of the invention. Similar references in
the drawings indicate similar elements.

[0008] FIG. 1 illustrates a film or video set using a remotely adjustable
diffusion panel, according to one embodiment.

[0009] FIG. 2a illustrates no/low diffusion through an adjustable
diffusion panel, according to one embodiment.

[0010] FIG. 2b illustrates medium diffusion through an adjustable
diffusion panel, according to one embodiment.

[0011] FIG. 2c illustrates high/full diffusion through an adjustable
diffusion panel, according to one embodiment.

[0014] FIG. 5a illustrates exemplary material for an adjustable diffusion
panel in one state of transmittance, according to one embodiment.

[0015] FIG. 5a illustrates exemplary material for an adjustable diffusion
panel in another state of transmittance, according to one embodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0016] In the following detailed description, numerous specific details
are set forth in order to provide a thorough understanding of the present
invention. However, those skilled in the art will understand that the
present invention may be practiced without these specific details, that
the present invention is not limited to the depicted embodiments, and
that the present invention may be practiced in a variety of alternate
embodiments. In other instances, well known methods, procedures,
components, and systems have not been described in detail.

[0017] Various operations will be described as multiple discrete steps
performed in turn in a manner that is helpful for understanding the
present invention. However, the order of description should not be
construed as to imply that these operations are necessarily performed in
the order they are presented, nor even order dependent.

[0018] As an overview, a film or video set 100 using a remotely adjustable
(or remotely controllable active) diffusion panel 106, according to one
embodiment, is shown in FIG. 1. When illuminating a subject 112 with a
light source 104 for the purpose of photography, videography, motion
picture capture, or theater, it is often desirable for the light source
104 to deliver light that is "soft" in nature/character. A light source
that delivers such light is often referred to as a "soft source" and is
an illumination that appears to emanate from a large area, thereby
casting shadows that have gradual transitions from light to dark, or
"soft shadows". In contrast, a "hard source" is an illumination that
appears to emanate from a point source such as a single bulb or filament,
thereby casting "hard shadows" that have a distinct and deliberate
transition from light to dark.

[0019] Most of the illumination sources used are point source type lights
such as filament-based incandescent bulbs. Such lights cast harsh or
distinct shadows. Various methods of light diffusion may be used to help
soften the light source as its light appears to the subject. One method
to soften the light is to place a relatively large piece of
semi-transparent material between the hard light source and the subject
to diffuse the hard light. The diffusion material is illuminated on one
side by the hard light source and appears to glow relatively uniformly on
the opposite side which faces the subject. The subject then appears to be
illuminated by a soft light source effectively as large as the
illuminated surface of the diffusion material.

[0020] Choosing among different diffusion materials most commonly involves
choosing material that has particular transparency characteristics. A
material with high transparency will make a hard source only slightly
softer (if at all) while a more opaque material will be the most
effective at softening a hard source. Each subject or lighting situation
may require a unique level of diffusion to give "just the right look",
and no single diffusion material having a particular transparency may
provide the "right" amount of diffusion for every situation.

[0021] Consequently, throughout a typical filming shoot the diffusion
material (and thus the transparency of the material) is often changed
multiple times before the desired level of diffusion appropriate to the
subject is achieved. The process of selecting the correct diffusion
requires having a wide selection of different grades of diffusion
materials on hand, and the physical action of removing and replacing the
diffusion material near the light source, which often is placed in
locations (i.e. overhead structure 102) requiring a ladder or other type
of scaffold or lift for sufficient access for placement of the diffusion
material.

[0022] As shown in FIG. 1, a active diffusion panel 106 having diffusion
material that has an electrically adjustable level of transparency may be
used to soften the otherwise hard light 108 from a point source light
104. The light transmitted 110 to the subject 112 can be selectably
changed in terms of its softness using a remote control 118 to vary the
degree of transparency of the (active) material used in the diffusion
panel 106. The remote control 118 is preferably connected to the panel
106 by wires 116, but in other embodiments the control 118 may wirelessly
communicate with the (active) panel 106. Using an active panel 106 that
is adapted to provide a range of transparency from clear (or transparent)
to substantially opaque eliminates the need for the user 120 or other
lighting crew members to physically change the diffusion material to
achieve different levels of diffusion and lighting at the subject. The
active material in the panel 106 may be adjusted by the user (camera
operator or other crew member) 120 at will during the film shoot to
compensate for changing levels of natural light, changes in desired
overall illumination, or simply to satisfy the visual goals of the
photographer.

[0023] FIGS. 2a-2c illustrate different levels of diffusion that are
preferably provided using an electrically adjustable diffusion panel 106.
Conventional diffusion paper ranges from 1/4 stop diffusion paper to full
or 1 and 1/4 stop paper. Light diffusion or 1/4 stop paper is more
transparent and only slightly softens the shadows/shadow edges. Medium
diffusion or 3/4 stop paper softens the shadow edges more, causing shadow
edges to fade. And heavy diffusion, such as "Lee Filters #216" (brand
named) full stop paper causes shadow edges to fade and blend in so the
shadows are nearly completely eliminated.

[0024] FIG. 2a illustrates the active panel 106 in a fully transparent
mode 214. In such a mode 214 the panel 106 allows the light 108 projected
from light source 104 to appear to the subject 112 without any
scattering. The shadows 220 from such setting of the adjustable panel 106
have sharp edges, and the light transmitted 202 is unsoftened. Viewed
from the subject 112, the light source 104 behind the panel 106 may be
represented as shown in view 208, indicating that the light source 104
remains an unsoftened point source of light. In the view 208, the panel
material is fully transparent, without color. As the diffusion setting
214 is adjusted to provide some diffusion, the view 208 starts to take
on, in preferred embodiments, a whitish or cloudy appearance.

[0025] FIG. 2b illustrates a medium diffusion setting 216, where the
transmitted light 204 is diffused (or scattered) to a medium setting 216
whereby the incident light 108 is scattered somewhat as it passes through
the panel 106. With such setting 216, the shadow 222 is softened so as to
lose its distinct edges, and viewing the panel 106 from the view point of
the subject 112 may be represented as shown in view 210, indicating that
the light source behind the panel 106 has become softened and made less
distinct. With the medium setting 216 the panel 106 material in view 210
takes on a whitish appearance, and the detail of the light source 104 is
lost due to the scattering of light allowed through the diffusion
material.

[0026] FIG. 2c illustrates a heavy diffusion setting 218, where the
transmitted light 206 is now diffused (or scattered) to a heavy setting
218 whereby the incident light 108 is heavily scattered as it passes
through the panel 106. With such setting 218, the shadow 224 is softened
so as to be nearly eliminated, and viewing the panel 106 from the view
point of the subject 112 may be represented as shown in view 212,
indicating that the light source behind the panel 106 has become nearly
undefined. With the heavy setting 218 the panel 106 material in view 212
takes on a more uniformly whitish appearance, and even the outline of the
light source 104 is lost due to the scattering of light allowed through
the diffusion material. Adjusting the diffusion of panel 106 to an even
heavier (i.e. more diffused) setting preferably causes the panel 106 to
become opaque, presenting a view to the subject 112 of a solidly
(uniformly) whitish panel. At such a setting, the opaque panel fully
blocks the subject 112 from view of the light source 104.

[0027] In preferred embodiments, the diffusion provided by panel 106 may
be adjusted using a remote control 118 from completely transparent (no
diffusion/scattering of the incident light from the light source 104) to
fully opaque (complete scattering of the incident light from the light
source 104), with the adjustment of diffusion being continuous so that
the user 120 may select from any amount of transparency using the control
118, from full transparency to no transparency and any selection of
transparency therebetween. In other embodiments, the diffusion provided
may be adjusted between nearly transparent to nearly opaque, with any
selection of transparency therebetween. In still other embodiments, the
diffusion may be adjusted so as to correspond with diffusion papers or
filters or scrims available in the film and video industry. For example,
the diffusion setting 214 may correspond with 1/4 stop diffusion papers
commonly available, setting 216 may correspond with 3/4 stop papers
available, and setting 218 may correspond with full stop papers
available. In one embodiment, the control 118 may include detents at
various commonly used settings or settable/resettable/programmable
presets for the convenience of the user 120 to return to desired
diffusion settings.

[0028] Although any type of light source may be used, the light source 104
is preferably a cool light source such as LED or fluorescent lighting.
Commonly used incandescent or other hot type lighting may be used with
sufficient shielding incorporated into panel 106, with sufficient spacing
between the light source 104 and the panel 106, and/or with use
sufficient cooling means (such as fans, heat sinks, favorable
ambient/cooling temperatures, etc.). Preferably, LED lighting such as
lighting provided by Zylight LLC (www.zylight.com) is used for the light
source 104. Suitable lighting is also described in the application for
U.S. letters patent, application Ser. No. 11/423,443 filed on Jun. 11,
2006, which is hereby incorporated by reference herein in its entirety,
and which describes wirelessly controllable and wirelessly networked LED
lighting modules.

[0029] Referring to FIG. 3, multiple remotely controllable diffusion
panels 104 may be used together. For example, a typical film or video
production set may include the lighting set up 300 shown in FIG. 3,
including a key (or primary) light source 104, a fill light 302, a back
light 304, and a background light 306. In preferred embodiments, each of
the active diffusion panels 106 may be remotely electrically controlled
so as to provide desired levels of diffusion. The panels 314 and 308 may
be set, for example, to medium-to-heavy diffusion settings for
transmitting diffused light 322 and 318, respectively. The panels 310 and
312, similarly, may be set, for example, to lower diffusion/greater
transparency settings for transmitting diffused light 320 and 316,
respectively.

[0030] Referring to FIG. 4, the components 400 of an exemplary adjustable
diffusion panel 106 preferably include active material 408 that provides
a range of electrically selectable degrees of transparency, frame
fastening material 402 for affixing the active material 408 to a rigid or
semi-rigid frame 404, and a controller 414 having circuitry adapted to
control an electrical potential applied to the material 408 causing the
material to change its transparency in response to the electrical
potential selected by the user of the controller 414 and thereby applied
to the active material 408. In one embodiment the controller includes a 9
volt battery, a potentiometer or other potential changing selection knob
416, wires 412 for delivering an electrical potential (i.e. voltage) to
the material 408 via a connection 410. Preferably the material 408 and
frame fastening material 402 (which may be a magnetic backed material,
Velcro type material, or other material preferably easily removable from
rigid or semi-rigid frame 404) are rollable 406 so as to facilitate easy
mobility from shoot to shoot. Other structures may be used in place of
the frame 404, and other shapes of the frame 404 may be used.

[0031] Preferable sizes include a 2 foot by 2 foot diffusion panel 106, a
3 foot by 3 foot version, and a 4 foot by 4 foot version. Other sizes may
be fabricated. Generally, any size and any shape (square, rectangular,
irregular, circular, etc.) may be used. Preferably the surface area of
the material 408 is large relative to the light source 104 for most
applications. An electrically adjustable active diffusion panel 106 may
also be used, however, with panel lights (such as the IS3 by Zylight LLC)
in soft box or other applications.

[0032] The active material 408 may comprise any material whose
transparency may be electrically adjusted from transparent (or nearly
transparent) to opaque (or nearly opaque). In preferred embodiments, the
material 408 comprises a polymer dispersed liquid crystal (PDLC) film
between layers of flexible, transparent plastic that include a thin layer
of conductive, transparent material. The conductive material form
transparent electrodes with liquid crystal droplets trapped therebetween,
and the liquid crystal droplets align together in varying degrees in
response to a voltage applied across the electrodes. With greater
voltage, more of the liquid crystals align thus increasing the material's
effective transparency.

[0033] FIG. 5a illustrates a cross-section 500 of material 408, according
to one embodiment, where the material 408 is in an "off" state, and FIG.
5b illustrates a cross-section 502 of material 408 where the material 408
is in an "on" state.

[0034] As shown in FIG. 5a, with no applied voltage 512, transparent
electrodes 520 and 522 do not cause any alignment of the liquid crystal
droplets 526, 528, and 524. Therefore, because each of the liquid
crystals transmits light in one direction 530 and blocks light in a
perpendicular direction 532, the cross-section 500 causes incident light
508 to scatter 510 rather than allow transmittance of the light 508
through the PDLC matrix.

[0035] As shown in FIG. 5b, the cross-section 502 allows incident light
506 to pass through the PDLC matrix as transmitted light 504 due to the
alignment of the liquid crystals 534, 536, and 540 in response to a
voltage 514 applied to the transparent electrodes 518 and 516. The degree
of transparency depends upon the voltage applied and degree to which the
liquid crystal droplets align together. As shown, the liquid crystals
534, 536, and 540 are all aligned so as to allow incident light to pass
through. As the voltage is varied, the alignments are changed causing the
material to scatter incident light and take on a milky white or cloudy
appearance. For example, reducing the voltage applied to electrodes 518
and 516 preferably causes the liquid crystal 540 to spin out of alignment
such that the direction 538 is no longer aligned with the incident light
506 and the direction 542 begins to block the incident light 506.

[0036] Although the material 408 in preferred embodiments is constructed
as shown and operates as described in FIGS. 5a and 5b, other
arrangements, materials, and configurations may be used that provide the
desired electrically adjustable transparency adapted for a diffusion
panel 106 as shown and described herein.

[0037] The terms and expressions which have been employed in the forgoing
specification are used therein as terms of description and not of
limitation, and there is no intention in the use of such terms and
expressions of excluding equivalence of the features shown and described
or portions thereof, it being recognized that the scope of the invention
is defined and limited only by the claims which follow.